A catheter introducer is a device that is placed, usually percutaneously, into a patient's body, such as into the vascular system for angiographic, angioplasty or other medical procedures. A catheter introducer typically includes a tubular shaft that is insertable into the patient's vascular system or other body region and a housing attached to the proximal end (the end disposed outside of the patient) of the tubular shaft. The housing contains and supports one or more self-sealing hemostasis gaskets that close to prevent blood leakage when no instrument is present in the introducer and to maintain a seal against and about such instrument to prevent blood loss while the instrument is in place through the introducer.
In addition to providing a hemostasis seal, both when an instrument is or is not present in the introducer, it is important that the gasket presents minimal drag and resistance to movement to the catheter, guidewire or other instrument in order to facilitate manipulation of the instrument in the patient. The tactile response that the physician senses at the proximal end of the instrument is important to the physician in order that he can feel obstructions or tortuous vascular anatomy as the instrument is advanced through that anatomy. Typically, hemostasis gaskets for catheter introducers have involved a compromise between maintaining an effective seal under all conditions of use and the resistance to movement that the gasket imposes on a medical instrument.
Prior art devices have addressed the desirability of maintaining a seal without: unduly impairing the ease of movement of the catheter through the gasket. Introducers may be made with self-sealing gaskets adapted to receive and effect a seal only with instruments having a limited range of diameters. That typically has been less than satisfactory because it is common to require the use of a number of guidewires and catheters that must be inserted through the introducer having diameter ranges of between about 0.035 inch to 0.118 inch or more. The self-sealing hemostasis gaskets disclosed in U.S. Pat. Nos. 4,000,739 (Stevens) and 4,424,833 (Spector) are representative of prior art gaskets designed to receive a specific size of instrument and adapted to accommodate a relatively limited range of instrument diameters.
U.S. Pat. No. 5,304,156 (Sylvanowicz) assigned to the assignee of the present invention discloses an improved catheter and guidewire introducer that has a self-sealing gasket adapted to effect a seal both in the presence and in the absence of a guidewire or catheter and where the range of diameters of guidewires and catheters that can be accepted is substantially greater than the art that preceded it, including the devices described in the Stevens and Specter patents. Moreover, the device described in the Sylvanowicz patent effected a seal over a wide range of devices while not significantly impairing the feel of the catheter as it is manipulated through the introducer. Notwithstanding the improvements achieved with the device described in the Sylvanowicz patent, it would be desirable to further improve the device by further reducing the drag imposed on the catheter or the guidewire by the gasket while still maintaining an effective hemostasis seal. Additionally, it would be desirable to enhance the manner in which the gasket is anchored in the housing, particularly so that when relatively large diameter catheters are inserted through the gasket, the gasket is retained securely in place in the housing and will resist any tendency for the relatively large diameter catheter to dislodge the gasket. It also is appreciated that instruments presented to the gasket off angle may dislodge the gasket from the housing, which could lead to a loss of hemostasis. An introducer which prevents detachment of the gasket in such situations would be desirable. It is among the objects of the present invention to provide such an improved introducer and gasket.